1. Field of the Invention
The present invention relates to an asphaltene solvent system for use in oil and gas wells. More particularly, it is concerned with an amine-activated dialkyl disulfide oil capable of dissolution of asphaltene deposits in an oil-bearing formation and producing well.
2. Description of the Prior Art
The deposition of asphaltenes during production or processing of oil from oil-bearing formations, and the problems associated with such deposition, for example, plugging of the formation, of the casing or tubing string, fouling of the surface equipment, or reduction in the desired flow of crude oil, are all well known. Whenever a crude oil contains high concentrations of asphaltenes, safeguards to inhibit the precipitation of asphaltenes and methods to remove unwanted asphaltene depositions during production or processing are employed.
Various methods have been employed for removal of asphaltene deposits including the use of solvent compositions to contact and dissolve the asphaltenes, and physical methods such as scrapping or treatment with hot petroleum oils. Additionally, carbon disulfide has been employed as a solvent for removal of asphaltene deposits from oil-bearing formations.
However, all of the above methods suffer from various deficiencies and have achieved only limited commercial success. For example, carbon disulfide is extremely hazardous and due to its low flash and auto-ignition points, its use is virtually precluded despite being one of the most effective asphaltene solvents known. The use of other known asphaltene solvents, such as stable halogenated organic compounds, in oil-bearing formations is also not preferred because of the risk of solvent carryover to the refinery where the solvents can poison cracking catalysts. Methods such as those disclosed in U.S. Pat. No. 3,689,319, issued to T. E. Sample, et al. on Sept. 5, 1971, and entitled "Paraffin Removal Process", suffer in that such methods are expensive thereby lessening the likelihood of their commercial use.
In view of the urgency of the energy supply situation in this country, treatment of asphaltic crude oil formations will become more desirable and necessary in the future. Hence, an economical, effective method for treatment of these formations to remove asphaltene deposits is necessary.